Chromizing of plasma nitrided AISI 1045 steel

In this study AISI 1045 steel specimens were plasma nitrided at 803 K for 5 h, in a gas mixture of 75% N(2) + 25% H(2). The specimens were then chromized in powder mixtures consisting of ferrochromium, ammonium chloride and alumina at 1273 K for 5 h. Scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and Vickers micro-hardness test were used as characterizing techniques. The thickness of white nitrided layer was around 5 mu m, which was mainly composed of iron nitrides and its hardness was around 740 HV. Chromizing of nitride layer resulted in formation of Cr(2)N chromium nitride and Fe(3)N iron nitrides. A significant increase was observed in hardness after chromizing of the nitrided layer. Despite its higher hardness, the post chromised specimen showed higher wear rate than single plasma nitrided specimen. (C) 2011 Elsevier B.V. All rights reserved.